STUDIES OX THE PHENOMENA OF CONTACT. 399 



If wc place a very small quantity of one of tliese bodies on ozonoscopic 

 paper, and expose the whole to the air, we shall perceive that at the end of a 

 quarter of an hour the paper begins to be colored, and the coloration proceeding 

 from the deposit extends itself further and further. The same thing takes place 

 with solid fats, stearine, margarine, &c., and with the fixed oils. One of 

 the Substances which most readily undergoes eremacausis is liquid sugar, 

 especially if it has been extracted from honey. If wc place some of this sugar, 

 already embrowned by the action of oxygen, at the bottom of a i3ask, and sus- 

 pend from the stopper an ozonoscopic paper, this last becomes colored in a very 

 short time.* There are reasons, also, for thinking that starch itself, under 

 certain circumstances, transforms oxygen into ozone, and here lies, in my 

 opinion, the cause of the discussions which have lately arisen on the eiiicacy 

 of this paper as a reagent for ozone ; iodurettcd starch, when dry and 

 placed beyond the influence of disturbing agents, such as hyponitric acid, &c., 

 is an excellent test for ozone ; but ioduretted starch, wet and exposed to 

 the solar light, can furnish only doubtful results, to say the least, for, in under- 

 going eremacausis, it should transform oxygen into ozone like other organic 

 bodies. There can never be a doubt of the presence or absence of ozone Avheu 

 we employ mineral reagents, such as sulphurous acid, the black sulphuret of lead, 

 which ozone immediately transforms into sulphuric acid and into white sulphate 

 of lead ; or even with the blue sulphate of indigo, with which ozone produces 

 colorless tsatine. 



The ethers and the alcohols while absorbing oxygen also transform it into 

 ozone. Sulphuric ether, in this instance, promptly discharges the color 

 from a solution of indigo. A solution of iodide of potassium in alcoholic ether 

 soon yields a precipitate of iodine through the action of the air, (a fact well 

 known to photographers who employ collodion,) because ether attracts oxygen 

 and converts it fnto ozone. Ordinary oxygen, it is known, docs not precipitate 

 the iodine from the iodide of potassium. Moreover, the acetic acid produced during 

 the reaction of air on alcoholized ether is not the cause of the precipitation 

 of the iodine, as we may convince ourselves by direct experiment. In fact, if 

 acetic acid be added to the solution of iodide of potassium in alcoholized ether, 

 %e iodine is not precipitated until after the lapse of several hours. When this 

 jaixture is oxidized, on the contrary, the precipitation of the iodine commences 

 immediately. This phenomenon may be artiiicially produced by plunging an 

 iron wire, heated to redness, into a mixture of the vapor of ether and air ; by 

 then pouring ioduret of potassium into the flask the iodine is at once disengaged. 

 This last experiment was devised, I believe, by M. Ilardwich. 



We may add to what has been just said in relation to organic bodies, that M. 

 Schonbein, by employing the alcoholic solution of the resin of guaiacum, has 

 succeeded in proving that the oxygen furnished by the action of heat on the 

 oxides of gold, of mercury, of platina, of silver, as well as on the peroxides 



* This is one of the first experiments which demonstrated to mo that organic bodies can 

 transform oxygen into ozone. This action of sugar on oxygen may be made manil'est in 

 another manner. If we pkmge a bit of metal — iron, for instance — into a solution of any sort 

 of sugar, we observe that the iron is rapidly and thoroughly oxidized where the metal is in 

 contact with the sugar and the air; that is, at the surface of the liquid. If the metal is com- 

 pletely submerged in tlie solution it is not oxidized at all, or, at least, a very long time must 

 elapse for oxidation to manifest itself. The corrosive action which sugar exerts on iron was 

 long since observed, and the captains of iron trading-vessels are often averse to carrying 

 cargoes of sugar for this reason. This corrosive action is owing to the fact that sugar (es- 

 pecially impure sugar or molasses) transforms the oxygen of the ambient air into ozone, which 

 actively attacks the iron where it is in contact with the sugar and the air. The result, in the 

 expei imeut above cited, is the formation of an abundant red precipitate, the larger part of 

 which is oxide of iron. A combination is at the same time formed, which has been anal^'zed 

 by Dr. Gladstone, and which is (C^ H'' O" FeO. ) It is impossible to produce tliis combiiia- 

 tion directly with sugar and the iron oxide. JIany otiier metals are attacked like iron wtcn. 

 placed in these circumstances — copper less than the other.s. 



